Centrifugal separators in and of themselves and the use of air cleaner assemblies which incorporate a plurality or bank of centrifugal separators are known in the prior art.
U.S. Pat. No. 3,713,280 issued to Keller et al discloses the construction of a typical prior art centrifugal separator. Centrifugal separators are generally tubular in construction. The separators form a spiral stream or flow of particulate-laden air passing through a tube. The spiral flow is induced either by placing a deflector in the tube in the path of an incoming air flow, or by introducing the air flow tangentially to the tube wall. Since the particles of material intermixed with the incoming air are relatively heavy, they are thrown outwardly to the periphery of the spiral.
The air at the center of the spiral is left relatively free of particulate material. The clean air is normally drawn off from the center of the tube and the particulate material is collected at the periphery of the tube. In order to obtain a large capacity for particulate material removal a plurality of centrifugal separators are arranged in an assembly. A scavenging air chamber is formed around the particulate material outlet of the tubes, and the clean air passes to the exterior of the scavenging air chamber. Assemblies of this type have been employed with diesel and gas turbine engines to clean the air entering the engine. Such assemblies have been used on engines in earth moving equipment, marine equipment, stationary power plants, over-the-road vehicles and aircraft.
U.S. Pat. No. 3,483,676 issued to Sargisson discloses an air cleaner assembly wherein a plurality of centrifugal-type separators are disposed in a frusto-conical shaped configuration. The frusto-conical shaped assembly is attached to the inlet end of a helicopter's gas turbine engine.
U.S. Pat. No. 3,520,114 issued to Pall et al and U.S. Pat. No. 3,915,679 issued to Roach et al each disclosed air cleaner assemblies wherein a plurality of centrifugal or vortex type air cleaners are arranged in a generally flat configuration. That is, all of the centrifugal separators are arranged generally parallel to one another. The Pall et al and the Roach et al patents each discuss the problem of pressure distribution within a scavenging chamber when a single scavenging outlet port is utilized. The Pall et al patent attempts to overcome this problem by the use of a plate 50 to adjust the pressure drop from an inlet 54 of each tube to the scavenging chamber 52. The Roach et al patent attempts to overcome this problem by the use of flow restrictors within the tubes of the centrifugal separators.